Degenerative retinopathies such as age-related macular degeneration or retinitis pigmentosa are leading causes of blindness world-wide. Both pathologies involve the loss of function in photoreceptor cells in the retina. As such, partial or complete blindness often results even though the neural wiring connecting the eye to the brain is intact.
Accordingly, one approach to overcome blindness has been focusing on the development of photosensitive implants to bypass the damaged photoreceptors in blind patients. Exemplary microelectronics-based macroscopic implants operate similarly to cochlear implants for hearing loss by providing electrode-induced electrical stimulation of the ganglion cells that in turn provide signals to the optic nerve. The retinal ganglions so stimulated electrically convey signals to the brain, and thereby afford blind patients limited vision. While encouraging, such macroscopic implants are far from ideal. Physically, they are still very limiting in terms of their size, weight, and external power requirements. Functionally, they are suffer from the problem that the patient's field of vision moves with every head movement.
US 20030022374 describes an alternative approach in which the photoresponsiveness of the photoreceptors is restored. In this approach, an optical trigger such as a photosystem I reaction center is incorporation into a cell.
US 20070028928 describes a more general approach involving the localization of nano- and micro-particle solar cells within and among excitable biological cells to controllably regulate membrane polarization of such cells.
Presently, no treatment is available for restoring vision lost to retinitis pigmentosa or age-related macular degeneration. Thus, there still exists an unmet need for a way to treat such debilitating diseases.